Networks are the principal means for communicating multimedia between communication devices. The content of the multimedia can include data, audio, text, images, video, etc. Communication devices include input/output devices, computers, terminals, multimedia workstations, fax machines, printers, servers, telephones, and personal digital assistants.
A multimedia network typically includes network switches connected to each other and to the communication devices by channels or circuits. The circuits can by physical or virtual. In the latter case, the circuit is specified by a source and destination address. The actual physical circuit used will vary over time, depending on network traffic and resource requirements and data capacity availability, usually expressed as “bandwidth.”
The multimedia can be formatted in many forms, but increasingly it is formatted into packets. Packets in transit between the communication devices may temporarily be stored in buffers at the switches along the path of the circuit pending sufficient available bandwidth on subsequent circuits along the path.
Important considerations in network operation are admission control and resource allocation. Typically, admission control and resource allocation are ongoing processes that are performed periodically during transmission of bit streams. The admission control and resource allocation determinations may take into account various factors such as network topology and current available network resources, such as buffer space in the switches and the bandwidth capacity of the circuits, any quality-of-service commitments (QoS), e.g., guaranteed bandwidth, and delay or packet loss probabilities.
If the network resource requirements are over-estimated, then the network will run under capacity. Alternatively, if the network resources requirements are underestimated, then the network may become congested and packets traversing the network may be lost, see, e.g., Roberts, “Variable-Bit-Rate Traffic-Control in B-ISDN,” IEEE Comm. Mag., pp. 50–56, September 1991; Elwalid et al, “Effective Bandwidth of General Markovian Traffic Sources and Admission Control of High Speed Networks,” IEEE/ACM Trans. on Networking, Vol. 1, No. 3, pp. 329–343, 1993. Guerin et al., “Equivalent Capacity and its Application to Bandwidth Allocation in High-Speed Networks,” IEEE J. Sel. Areas in Comm., Vol. 9, No. 7, pp. 968–981, September 1991.
Transmission of digital multimedia over bandwidth-limited networks will become increasingly important in future Internet and wireless applications. It is a challenging problem to cope with ever changing network parameters, such as the number of multimedia sources and receivers, the bandwidth required by each stream, and the topology of the network itself. Optimal resource allocation should dynamically consider global strategies, i.e., global network management, as well as local strategies, such as, admission control during individual connections.
Admission control and resource is generally done at the “edges” of the network in order to conserve computational resources of the network switches. While off-line systems can determine the exact bandwidth characteristics of a stream in advance, in many applications, on-line processing is desired or even required to keep delay and computational requirements low. Furthermore, any information used to make bandwidth decisions should be directly available in the compressed bit stream.
As a characteristic, prior art admission control methods either grant or deny the request for service. In the prior art, admission control is applied to an incoming request for a single transmission medium between a source and a destination.
Knightly et al. in “D-BIND: An accurate traffic model for providing QoS guarantees to VBR traffic,” IEEE Tr. Networking, vol. 5, no. 2, pp. 219–231, 1997, describe introduces a traffic model for providing performance guarantees in integrated services networks. That model consists of a number of rate-interval pairs that are specified to the network at connection set-up time. However, for the online case, the arrival sequence is not known in advance and hence, parameter values for any traffic model are more difficult to obtain than in an off-line case. In that model, the admission criteria is a function of the deterministic delay bound,
Therefore, there is a need for an improved method and system for dynamically allocating network resources at renegotiation points while transferring multimedia content over a network.